GSK said it plans to begin a Phase 3 efficacy trial of its seasonal mRNA flu vaccine in September 2026, following positive Phase 2 results.
The Phase 2 Flu-028 study enrolled 971 adults. The vaccine generated stronger immune responses than licensed standard-dose vaccines in younger adults and high-dose vaccines in older adults, while showing an acceptable short-term safety and inflammatory profile.
GSK will advance an optimized formulation containing a B-strain hemagglutinin (HA) design, known as FLUm3HA.b-3NA.
Unlike most current flu vaccines, the candidate targets both hemagglutinin (HA) and neuraminidase (NA)—surface proteins involved in viral entry and spread.
If launched as planned, this would be the first late-stage mRNA flu-vaccine trial specifically designed to target both HA and NA. The program could compete with Moderna’s recently approved mRNA flu vaccine, mFlusvia.
The Phase 3 study will still need to establish clinical efficacy and safety; stronger antibody responses in Phase 2 do not guarantee protection against influenza or regulatory approval.
Sources:
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Study Details | NCT07204964 | ClinicalTrials.gov - ClinicalTrials.gov